# TCP chat server
# select module provide asynchronous I/O
import socket, select

# Function to broadcast chat message to all connected clients
def broadcast_data(sock, message):
	#Do not send message to master socket and client who has send us the message
	for socket in CONNECTION_LIST:
		if socket != server_socket and socket != sock:
			try:
				socket.send(message)
			except:
				# broken socket connection may be, chat client pressed Ctrl-C for example
				socket.close()
				CONNECTION_LIST.remove(socket)

if __name__ == "__main__":

	# List to keep track of scoket descriptors
	CONNECTION_LIST = []
	RECV_BUFFER = 4096 # Advisable to keep it as an exponet of 2
	PORT = 5000

	server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
	# this has no effect, why?
	server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
	server_socket.bind(("0.0.0.0", PORT))
	server_socket.listen(10)

	# Add server socket to the list of readable connections
	CONNECTION_LIST.append(server_socket)

	print "Chat server started on port " + str(PORT)


	while 1:
		# Get the list sockets which are ready to be read through select
		read_sockets,write_sockets,error_sockets = select.select(CONNECTION_LIST, [] ,[])

		for sock in read_sockets:
			# New connection
			if sock == server_socket:
				# Hand the case in which there is a new connection recieved through server_socket
				sockfd, addr = server_socket.accept()
				CONNECTION_LIST.append(sockfd)
				print "Client (%s, %s) connected" % addr

				broadcast_data(sockfd, "[%s %s] entered room\n" % addr)

			# Some incoming message from client
			else:
				# Data received from client, process it
				try:
					# In windows, sometimes when a TCP program closes abruptly,
					# a "Connection reset by peer " exception will be thrown
					data = sock.recv(RECV_BUFFER)
					if data:
						broadcast_data(sock, "\r" + '<' + str(sock.getpeername()) + '> ' + data)

				except:
					broadcast_data(sock, "Client (%s %s) is offline" % addr)
					print "Client (%s %s) is offline " % addr
					sock.close()
					CONNECTION_LIST.remove(sock)
					continue
	server_socket.close()

